Process for obtaining x-shaped filaments



Much 1970 R. STUCHLIK 3,499,958

PROCESS FOR-OBTAINING X'SHAPED FILAMENTS Filed Oct. 31, 1966 FIG. 2.

United States Patent 3,499,958 PROCESS FOR OBTAINING X-SHAPED FILAMENTSRene Stuchlik, Villeurbanne, France, assignor to Societe Rhodiaceta,Paris, France, a French body corporate Filed Oct. 31, 1966, Ser. No.590,711 Claims priority, applicatiol France, Nov. 8, 1965, 37 6 4 Int.01. D01d 3/00, 5/04 US. Cl. 264177 1 Claim ABSTRACT OF THE DISCLOSUREThe invention relates to a process for obtaining filaments thetransverse crosssection of which is in the shape of an X, and to aspinneret having a new type of perforation and intended to be used forthe said process.

It is already known to obtain filaments of X crosssection or Hcross-section by dry spinning a solution of a filament-forming materialin a volatile solvent, using a spinneret perforated with square holes.However, such processes generally yield yarns in which some filamentshave an 'H cross-section and others an X cross-section, without it beingpossible easily to obtain yarns in which all, or almost all, of thefilaments have an X crosssection. The hitherto known spinnerets withsquare holes have always been perforated in such a way that one of themedians of the square holes coincides with a radius of the spinneret.

The present invention provides a process for obtaining yarns in whichmost 'or practically all the constituent filaments have a transversecross-section in the shape of the letter X, which comprises dry spinninga solution of a filament-forming material in a volatile solvent througha spinneret perforated with square holes, such that the dryingconditions at two adjacent sides of each square hole are substantiallyidentical. Preferably a spinneret as described below is used.

The invention consists also in a spinneret perforated with square holeswhich may be used for this process, in which the said square holes areso arranged that each of them has one diagonal making an angle of lessthan with the radius of the spinneret which passes through the centre ofthe hole.

By filament-forming materials are meant synthetic or artificialpolymeric materials such as cellulosic esters, especially cellulosediacetate (secondary cellulose acetate) or triacetate, and syntheticpolymers.

The term volatile solvent is to be understood as any liquid capable ofdissolving the material to be spun, but having a relatively low boilingpoint, preferably not exceeding 80 C.

For reasons of convenience it is generally preferable to use the usualsolvents normally employed for dry spinning the filament-formingmaterial such as acetone for cellulose diacetate, a mixture of methylenechloride and a low aliphatic alcohol, especially methanol or ethanol,for cellulose triacetate, a mixture of carbon disulphide and acetone forpolymers based on vinyl chloride, etc.

Spiunerets of any shape and size, and made of any 3,499,958 PatentedMar. 10, 1970 appropriate material, may be used, depending on thematerial which is to be spun. The spinneret may for example be in theform of a plate or a dome and may be perforated with one or more ringsof holes. However, it is generally preferable, in the process of theinvention, to use a spinneret which does not have: too large a number ofrings of holes, or the rings too closely spaced, since in that case thefilaments issuing from the holes in the central rings may be producedunder poor drying conditions and may not have the expected shape. Thespinneret may, equally, be perforated with holes arranged along one ormore lines, for example along the sides of a polygon concentric with thespinneret. It will generally be advantageous to use a spinneret in whichthe perforations are not too close, so that the drying of each filamentis not interfered with by the presence of the adjacent filaments.

The same conditions of temperature of the spinning solution, temperatureof the walls of the spinning chamber, temperature and rate of flow ofco-operative medium, and of stretching on spinning, may be used as arenormally employed for dry spinning the same filamentforming material.

The process of the invention makes it possible to obtain yarns in whichat least of the constituent filaments have a cross-section in the shapeof an X. Such a cross-section gives the filaments special properties,principally very high resilience, this characteristic being particularlyappreciated and sought after in carpet piles.

The invention is illustrated in the accompanying drawings, in which:

FIGURE 1 is a view of the external face of a spinneret,

FIGURE 2 is a view of a portion of the spinneret face of FIGURE 1 on alarger scale,

FIGURE 3 is a view of the external face of another spinneret,

FIGURE 4 is a view of the external face of a third spinneret, and

FIGURE 5 shows the transverse cross-section of a filament obtained bythe process of the invention.

Referring now to FIGURE 1, there is shown a spinneret comprising a base1 and holes 2; arranged in one ring.

FIGURE 2 shows that the holes 2 are arranged in such a way that each ofthe diagonals 3, 3' and 3" coincides with a radius 4, 4 and 4" of thespinneret.

In FIGURE 3 the holes 2 are arranged in 3 rings each having 4 holes, oneof the diagonals of each hole coinciding with a radius of the spinneret.

In FIGURE 4, the holes 2 and 2 are arranged along the sides of a polygonconcentric with the spinneret face. The holes 2 are so oriented that oneof their diagonals coincides exactly with a radius of the spinneret, andthe holes 2' in such a way that one of their diagonals, makes an angleof 7 with a radius of the spinneret.

FIGURE 5 shows the shape of filaments 5 which all have a X-shapedcross-section.

The following examples, in which parts are by weight, illustrate theinvention.

This solution is warmed to 55 C. and extruded through a spinneret in avertical dry spinning chamber of internal diameter 60 mm. and height3.50 m., the walls of which are heated to C. The spinneret has 5 squareholes of side length 0.1 mm. arranged regularly in a ring of radius 30mm., a diagonal of each square coinciding with a radius of thespinneret. Air at the ambient temperature circulates through the chamberin a downward direction, i.e. in the same direction as the filaments ata rate of 4.5 m. /h. A 120 decitex (110 denier) yarn consisting of 5filaments each of 24 decitex (22 denier) is obtained at a speed of 150m./ minute; the filaments have an X crosssection such as is shown inFIGURE 5.

By way of comparison, filaments obtained from the same solution, andspun under the same conditions as before but using a spinneret in whichthe 5 square holes, though of the same size, are arranged in such a waythat one of the medians of each hole coincides with a radius of thespinneret, have an H cross-section.

EXAMPLE 2 A solution identical to that of Example 1 is heated to 60 C.and extruded through a spinneret having square holes of side length 0.08mm. oriented as in Example 1 and arranged in a ring of radius 30 mm., ina dry spinning chamber identical with that used in Example 1, but withthe walls heated to 115 C. and with the air passing down the chamber ata rate of 8 in. per hour.

A 130 decitex (120 denier) yarn consisting of 10 filaments each of 13decitex (12 denier) and each having an X cross-section, is obtained at aspeed of 200 m./ minute.

EXAMPLE 3 A solution containing the following is prepared:

Parts Cellulose triacetate 22 Methanol 11 Methylene chloride 67 Thissolution is heated 55 C. and extruded through a spinneret having 24square holes of side length 0.04 mm.

4 arranged as in FIGURE 1, in a dry spinning chamber identical to thatof Example 1 but with the walls heated to C.

Air is circulated down the chamber at a rate of 6 m5 per hour.

A 110 decitex denier) yarn consisting of 24 filaments each of 4.9decitex (4.4 denier) and each having an X cross-section is obtained at aspeed of 250 m./ minute.

I claim:

1. A process for obtaining yarns in which at least most of theelementary filaments have an X cross-section, which comprises drySpinning a solution of a cellulose acetate in a volatile solventselected from the group consisting of solutions of secondary celluloseacetate in acetone and solutions of cellulose triacetate in mixtures ofmethylene chloride and a lower aliphatic alcohol through a spinneretperforated with square holes, in which each hole has one diagonal makingan angle less than 10 with the radius of the spinneret face passingthrough the center of the hole, as a result of which the dryingconditions are substantially identical on two adjacent sides of eachsquare hole.

References Cited UNITED STATES PATENTS 1,902,953 3/1933 Hazell.2,880,106 3/ 1959 Hawtin 264-207 FOREIGN PATENTS 695,217 9/ 1964 Canada.

JULIUS FROME, Primary Examiner H. MINTZ, Assistant Examiner US. Cl. X.R.

